Several items meaning ‘goat’ have external comparanda, four are included here. See also Kroonen (2012: 245-247):
Gloss: ‘goat’ (item 15 in Bjørn 2017)
OHG ziga; Alb. dhi ‘fem. g.’; Gr. (Hes.) δίζα; Arm. tik ‘hide’; Ishkashimi (East Iranian) dec ‘goatskin bag’
Notes: The Greek form is problematic and requires either a glide to palatalize the velar, or, as has been suggested, the form in Hesychius, originally ascribed to Laconian, may rightfully be attributed to one of the lesser known IE Balkan languages, Thracian or Illyrian (Frisk 1960: 390ff.). All the data combined, this reconstruction still fails to paint the picture of a central PIE item, although proto-status certainly is possible.
NE Caucasian: *tVqV > e.g. Ingush tɨqo
HU: Hurrian taɣə ‘man (male person)’
Kartvelian: *dqa > Georgian txa, Svan daq–
The IE material does not seem to be particularly strong and lacks cognates in the decisive ancient branches. Proposed as a borrowing by Gamkrelidze & Ivanov (1995: 774) and Nichols (1997: 146), the exact nature of the reconstruction in Kartvelian is debated (cf. Fähnrich 2007: 125), but the Northeast Caucasian material does help establish the form in the region. The semantics of the Hurrian material questions its appurtenance, but a final rejection pends further illumination of the internal relationship. Ultimately, this item belongs in the very same category as the synonyms (items 21, 40, and 73, cf. § 18.104.22.168) and be ascribed to a loan into the later strata of PIE.
Gloss: ‘goat’ (item 21 in Bjørn 2017)
Lat. haetus ‘young g., kid’; Germ. *gait- > ON geit, Goth. gaits.
The connection of the Latin and Germanic forms seem beyond reproach, but remain isolated as a European regionalism. a-vocalism similarly makes a PIE origin of this item unlikely (Dolgopolsky 1987: 16).
Afro-Asiatic: Semitic *gadi-̯ > Arab. jadyun, Heb. ge?ī
Afro-Asiatic: Berber aġăyd
NE Caucasian: Proto-Nakh *gāʒa, Lak gada ‘kid’
The Semitic and IE correspondence is difficult to ignore, but whereas Dolgopolsky considers it a direct loan from Proto-Semitic into PIE (1987: 14), Kroonen proposes a (likely extinct and unattested) third party origin for both, ultimately stemming from waves of early agriculturalists that first introduced the term to Semitic and later into European IE from an already present adstrate (2013: 163ff.).The dearth of proper PIE evidence affects both theories, but less detrimentally the latter. Nichols’ analysis of the NE Caucasian forms as old dialectal borrowings due to the internal inconsistencies (1997:129) seems to
corroborate the adstrate hypothesis; it is noteworthy, however, that Nikolayev & Starostin reconstructs a Proto-NC *gēʒ́wV that would remove the Caucasian item from comparison with PIE and Afro-Asiatic. It seems callous to posit the root for PIE proper and invites further inquiry into the ancient relations of European IE and its agricultural prehistory (cf. *h1ln̥bh– ‘lamb’, item 36, for a similar correspondence between Germanic and NE Caucasian).
Gloss: ‘goat’ (item 40 in Bjørn 2017)
Alternant 1: *h2eiĝ-
Attestations: Alb. dhi; Gr. αἲξ; Arm. aic; (?)Ved. eḍa– ‘kind of sheep’, Av. īzaena- ‘leathern’
The Vedic form requires analogy to fit the picture, but seems plausible (cf. Mayrhofer 1986: 264). Attestations only warrant reconstruction for late PIE.
Alternant 2: *h2eĝ-
Lith. ožýs; OCS azno ‘goat-skin’; Alb. edh; Ved. aja-, Av. aza-
The homophonous verbal root *h2eĝ- ‘to lead’ (item 43) has quite naturally been
suggested as the derivational base, but the likeness to (1) complicates this connection (cf. also Mallory & Adams 1997: 229). This form also brands cognates in Balto-Slavic, but still fails to secure the decisive old branches for ancient strata.
North Caucasian: *Hējʒ́u (cf. *ʡējʒ́wē of NCED s.v. ‘goat, she-goat’)
The variant forms within (P)IE do suggest a foreign source, which, indeed, may
be found in North Caucasian, as suggested by S. Starostin (2009: 80 fn.8). This is certainly also suggested by the phonological compositions that are close to being superimposable, especially on reconstruction (1) with the diphtongue. The second reconstruction may under this paradigm be explained as either stemming from folk-etymological analogy with the homophonous verbal root *h2eĝ– ‘to lead’, or as the natural yet inconsequent treatment of a foreign sequence in (P)IE (cf. Matasović 2012: 290 fn.16). Further phonological confusion is encountered if PIE *h2egw-no- ‘lamb’ (item 45) is considered a derivative to the present form.
Gloss: ‘goat’ (item 73 in Bjørn 2017)
Old Low German hōken; OCS koza; Alb. kedh, kec ‘kid’
Very limited distribution questions ancient PIE moorings for this item. Connections with PIE *h2e(i)ĝ- (item 40) are formally impossible (cf. Mallory & Adams 1997: 229). The reconstructed a-vocalism is noteworthy.
NE Caucasian: *qoVcV > e.g. Lezgian ʁec
The Slavic forms may, according to Derksen, be borrowed from a Turkic language
relatively late (2008: 242), ostensibly within the first millennium CE. S. Starostin proposes this Northeast Caucasian connection (2009: 81), but the formal correspondence is not very attractive.